Other suggested explanations for the Abgar-Jesus legend
Drijvers, 159-62 [Suggests that the name of "Addai," a Manichean
missionary in Edessa, was bestowed retroactively on the fictitious emissary
from Thomas, as an anti-Manichean tactic];
Murray 5-9 [Suggests that legend of Addai was imported from Nisibis, east
of Edessa, which may have been the first site of Christianity in Mesopotamia];
Segal, 67-9.